Clarifying the Electronic Structure of Anion-Templated Silver Nanoclusters by Optical Absorption Spectroscopy and Theoretical Calculation

Yusuke Horita; Sakiat Hossain; Mai Ishimi; Pei Zhao; Miyu Sera; Tokuhisa Kawawaki; Shinjiro Takano; Yoshiki Niihori; Toshikazu Nakamura; Tatsuya Tsukuda; Masahiro Ehara; Yuichi Negishi

doi:10.1021/jacs.3c07194

Clarifying the Electronic Structure of Anion-Templated Silver Nanoclusters by Optical Absorption Spectroscopy and Theoretical Calculation

J Am Chem Soc. 2023 Nov 1;145(43):23533-23540. doi: 10.1021/jacs.3c07194. Epub 2023 Oct 20.

Authors

Yusuke Horita¹, Sakiat Hossain², Mai Ishimi¹, Pei Zhao³, Miyu Sera¹, Tokuhisa Kawawaki^{1

2}, Shinjiro Takano⁴, Yoshiki Niihori², Toshikazu Nakamura³, Tatsuya Tsukuda⁴, Masahiro Ehara³, Yuichi Negishi^{1

2}

Affiliations

¹ Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan.
² Research Institute for Science & Technology, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan.
³ Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan.
⁴ Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan.

Abstract

Electronic structures of anion-templated silver nanoclusters (Ag NCs) are not well understood compared to conventional, template-free Ag NCs. In this study, we synthesized three new anion-templated Ag NCs, namely [S@Ag₁₇(S-4CBM)₁₅(PPh₃)₅]⁰, [S@Ag₁₈(S-4CBM)₁₆(PPh₃)₈]⁰, and [Cl@Ag₁₈(S-4CBM)₁₆(PPh₃)₈][PPh₄], where S-4CBM = 4-chlorobenzene methanethiolate, and single-crystal X-ray crystallography revealed that they have S@Ag₆, S@Ag₁₀, and Cl@Ag₁₀ cores, respectively. Investigation of their electronic structures by optical spectroscopy and theoretical calculations elucidated the following unique features: (1) their electronic structures are different from those of template-free Ag NCs described by the superatomic concept; (2) optical absorption in the range of 550-400 nm for S^2--templated Ag NCs is attributed to the charge transitions from S^2--templated Ag-cage orbitals to the s-shaped orbital in the S^2- moiety; (3) the Cl^--templated Ag NCs can be viewed as [Cl@Ag₁₈(S-4CBM)₁₆(PPh₃)₈]⁰[PPh₄]⁰ rather than the ion pair [Cl@Ag₁₈(S-4CBM)₁₆(PPh₃)₈]^-[PPh₄]⁺; and (4) singlet-coupled singly occupied orbitals are involved in the optical absorption of the Cl^--templated Ag NC.